Total time spent on this project as of the latest entry: 0.45 hours

June 24th, 2025 [Introduction & Research] - 0.45 hours {IN PROGRESS}

This is my second project for Highway, and as such it will be a lot smaller than my previous one. yes, i REALLY want to go to Undercity. Also, the format for both the JOURNAL.md file as well as the folder containing the CAD files will be similar or exactly the same.

For this project, my goal is to design a very simple solder fume extractor that meets the following criteria: - Easy to build for beginners - Affordable ($15-20 USD cost goal) - Works well - Fan speed adjustable by a potentiometer/dial/encoder (PWM)

I began with researching types of fans and which would be a good one for this application. A fan that runs off of DC at a lower voltage would be preferred for this project, as I'd like to be able to power the unit via USB-C in the end. A couple fan types were of note, that fit my above criteria.

Standard 120/140mm PC Case Fan

Pros: - Inexpensive (approx. $5-10 USD) - Large(ish) size - PWM-driven - Widely available - 12V DC

Cons: - Many different styles, mounting holes might not line up on each - Connector/wiring differs slightly between each model

9025 Fan

Pros: - Inexpensive (approx. $4-5 USD) - Smaller size, but still large enough - Generic part available from sites like AliExpress - 12/24V DC

Cons: - Not PWM-driven

In the end, I chose to go with the PC case fan, in a 140mm size. This was mostly due to the fact that these are everywhere online, and don't cost that much. I now needed a way of actually controlling the fan's speed, and a microcontroller would be the simplest way of doing so. (one might be able to get away with using a 555 timer to generate the PWM signal, but I like to code and keep the physical electronics relatively simple).